Barcelona's 3-1 defeat by arch-rival Real Madrid on Wednesday came in the wake of its surprise 2-0 loss to AC Milan at the San Siro, prompting some critics to speak of a decline in fighting spirit at Camp Nou.
But the Spanish midfielder refuted those suggestions, insisting the Catalans will go on to have a successful season if they remain unaffected by the recent adversity.
"In situations where rivals overcome us we must accept it, but with the mindset that we have more [competitions] later we have to be optimistic," Iniesta told reporters following elimination from the Copa del Rey.
The 28-year-old added that Barcelona's thirst for success remains undiminished despite the huge trophy haul it has enjoyed over the last decade.
"The team has not let go and is not unwilling, that never happens."
Iniesta was also keen to look forward rather than back, highlighting the European and domestic targets on the horizon.
"The tie against Milan is complicated but we will play with the conviction that we must show [in the second leg].
"On Saturday we have a tough game at the Bernabeu and we have to keep the distance in the league."